PyQt5: The specified module could not be found
I remember that i ran into this error too. I think the problem was the qwindow.dll. 

For me the necessary steps were: install the correct PyQt5 version directly into the python directory of the binary. For 2.76 the PyQt folder has to be in the 2.76\python\lib\site-packages directory.Then you need to grab the qwindow.dll, put it into a folder called platforms, and put it asides the Blender exe. And you should be ready to go.